Unit 3 – The Chemistry of Engineering Materials Polymers

Question 1

Bold

A ___________ is a molecular compound that can be distinguished by a high molar mass, ranging into thousands and even millions of mass and they are made up of many repeating
units.

Answer 1

polymer

Question 2

_____________ were first developed in the early 20th century, and these polymers remarkably transformed our world as different materials can be created with properties that are ideal for different applications.

Answer 2

Synthetic (man-made) polymers

Question 3

Polymers that have been around
since life itself began.

Answer 3

Natural Polymers

Question 4

Cellulose, starch, and other complex carbohydrates are examples of

Answer 4

Natural Polymers

Question 5

It is a polymer obtained from rubber trees and even the code
for life itself, DNA, is a natural polymer.

Answer 5

Natural rubber

Question 6

Fill in the blanks

Because of the _________, we might expect that molecules containing thousands of carbon and hydrogen atoms can form a massive number of structural and geometric
isomers (if C=C bonds are present).

Answer 6

size polymers

Question 7

Bold

___________are the small molecules that are used for synthesizing polymers and each of it is analogous
to a link in a chain.

Answer 7

monomers

Question 8

Monomers (_____ meaning “one”; _____ meaning “unit”)

Answer 8

mono
meros

Question 9

Monomers ( mono meaning “____”; meros meaning “______”)

Answer 9

one
unit

Question 10

Bold

They can be created from one monomer, of from
a combination of two or more different monomers.

Answer 10

polymers

Question 11

Bold

If a polymer is made up of only type of monomer (e.g. polyethylene), then it is known as __________.

Answer 11

homopolymer

Question 12

Give three homopolymers that are synthesized by the radical mechanism

Answer 12

Teflon TM
polytetrafuoroethylene
poly(vinyl chloride) (PVC)

Question 13

___________ can be made from many different starting materials which usually come from crude oil (raw material).

Answer 13

Synthetic polymers

Question 14

___________ is the starting material for many
plastics, pharmaceuticals, fabrics, and other carbon-based products.

Answer 14

crude oil

Question 15

Bold

The molecules in polymers are gigantic and because of their size they are often referred to as __________.

Answer 15

macromolecules

Question 16

The backbone of each of a carbon-chain polymer is a string
of carbon atoms and within each molecule, the atoms are bound together by___________ bonds.

Answer 16

covalent interatomic

Question 17

Each of the two remaining valence electrons for every carbon atom may be involved in side bonding with atoms or radicals that are positioned adjacent to the chain. Of course,
both _____and __________ are also possible.

Answer 17

chain
side double bonds

Question 18

is a gas at ambient temperature and pressure which
has the following molecular structure.

Answer 18

hydrocarbon ethylene (C2H4)

page 126 for figure

Question 19

Under appropriate conditions, ethylene gas reacted and it will transform to ___________ which is a solid polymeric material.

Answer 19

polyethylene (PE)

Question 20

It is a solid polymeric material.

Answer 20

polyethylene (PE)

Question 21

transforming ethylene to polyethylene

This process begins when an active center is formed by the reaction between an __________ (R·) and the ethylene monomer.

Answer 21

initiator or catalyst species

Question 22

Next, the polymer chain forms by the __________ of monomer units to this actively growing chain molecule

Answer 22

sequential addition

Question 23

Other chemistry of polymer structure such as tetrafluoroethylene monomer to form
__________________ (PTFE)

Answer 23

polytetrafluoroethylene

Question 24

Italicize

Polytetrafluoroethylene (having the trade name Teflon) belongs to a family of polymers called the _____________.

Answer 24

fluorocarbons

Question 25

The ______________(CH2=CHCl) is a slight variant of that for ethylene, in which one of the four H atoms is replaced with a Cl atom.

Answer 25

vinyl chloride monomer

Question 26

vinyl chloride monomer leads to ____________

Answer 26

poly (vinyl chloride)

Question 27

enumerate the polymer structures

Answer 27

Linear Branched Crosslinked Network

Question 28

are those in which the repeat units are joined together end to end in single chains.

Answer 28

Linear Polymers

Question 29

-These long chains are flexible where each circle represents a unit.

Answer 29

linear

Question 30

-There may be extensive van der Waals and hydrogen bonding between the chains.

Answer 30

Linear

Question 31

-Some of the common polymers that form with ________ structures are polyethylene, poly(vinyl chloride), polystyrene, poly(methyl methacrylate), nylon, and the fluorocarbons.

Answer 31

linear

Question 32

-The chain packing efficiency is reduced with the formation of side branches, which results in a lowering of the polymer density.

Answer 32

Branched

Question 33

-For example, high-density polyethylene (HDPE) is primarily a linear polymer, whereas low-density polyethylene (LDPE) contains short-chain branches.

Answer 33

Branched

Question 34

-Adjacent linear chains are joined one to another at various positions by covalent bonds.

Answer 34

crosslinked

Question 35

-The process of __________ is achieved either during synthesis or by a nonreversible chemical reaction.

Answer 35

crosslinking

Question 38

is accomplished by additive atoms or molecules that are covalently bonded to the chains.

Answer 38

crosslinked

Question 39

-Many of the rubber elastic materials are ________.

Answer 39

crosslinked

Question 40

-These are multifunctional monomers forming three or more active covalent bonds make three- dimensional networks.

Answer 40

Network

Question 41

-A polymer that is highly crosslinked may also be classified as a _______ polymer.

Answer 41

network

Question 42

-These materials have distinctive mechanical and thermal properties; the epoxies, polyurethanes, and phenol-formaldehyde belong to this group.

Answer 42

network

Question 43

Presently, there are more than ___________ synthetic polymers known,

Answer 43

60,000

Question 45

six types of polymers

Answer 45

polyethylene LDPE (4) polyethylene HDPE (2) polyvinyl chloride PVC or V (3) polystyrene PS (6) polypropylene PP (5) polyethylene terephthalate PETE or PET (1)

Question 46

-Translucent if not pigmented. -Soft and flexible. -Unreactive to acids and bases. -Strong and tough.

Answer 46

polyethylene LDPE

Question 47

Bags, films, sheets, bubble wrap, toys, wire insulation.

Answer 47

polyethylene LDPE

Question 48

-Similar to LDPE -More rigid, tougher, slightly more dense.

Answer 48

polyethylene HDPE

Question 49

Opaque milk, juice, detergents, and shampoo bottles. Buckets, crates, and fencing

Answer 49

polyethylene HDPE

Question 50

-Variable. Rigid if not softened with a plasticizer. Clear and shiny, but often pigmented. Resistant to most chemicals, including oils, acids, and bases.

Answer 50

polyvinyl chloride

Question 51

Rigid: Plumbing pipe, house siding, charge cards, hotel room keys. Softened: Garden hoses, waterproof boots, shower curtains, IV tubing.

Answer 51

polyvinyl chloride

Question 52

-Variable. “Crystal” form transparent, sparkling, somewhat brittle. -“Expandable” form lightweight foam. -Both forms rigid and degraded in many organic solvents.

Answer 52

polystyrene

Question 53

“Crystal” form: Food wrap, CD cases, transparent cups. “Expandable” form: Foam cups, insulated containers, food packaging trays, egg cartons, packaging peanuts.

Answer 53

polystyrene

Question 54

-Opaque, very tough, good weatherability. High melting point. -Resistant to oils.

Answer 54

polypropylene

Question 55

Bottle caps. Yogurt, cream, and margarine containers. Carpeting, casual furniture, luggage.

Answer 55

polypropylene

Question 56

-Transparent, strong, shatter- resistant. - Impervious to acids and atmospheric gases. -Most costly of the six.

Answer 56

Polyethylene terephthalate

Question 57

Soft-drink bottles, clear food containers, beverage glasses, fleece fabrics, carpet yarns, fiber-fill insulation.

Answer 57

Polyethylene terephthalate

Question 58

_______________ is an alternative way of expressing average chain size of a polymer.

Answer 58

Degree of Polymerization (DP)

Question 59

The ______________ is obtained by dividing the chains into a series of size ranges and then determining the number fraction of chains within each size range

Answer 59

number-average molecular weight Mn

Question 60

A ____________is based on the weight fraction of molecules within the various size ranges.

Answer 60

weight-average molecular weight Mw

Question 61

two subdivision of polymers

Answer 61

thermoplastics thermosets

Question 62

they soften upon heating and later liquefy, then it hardens when cooled. This process is reversible and can be repeated.

Answer 62

thermoplastics

Question 63

Examples of common ____________________ polymers are polyethylene, polystyrene, poly(ethylene terephthalate), and poly(vinyl chloride).

Answer 63

thermoplastic

Question 64

For ________________ polymers which are network polymers, they do not soften upon heating and they become permanently hard during their formation.

Answer 64

thermosetting

Question 65

Examples of these _______________ (crosslinked and network polymers) are vulcanized rubbers, epoxies, phenolics, and some polyester resins.

Answer 65

thermosets

Question 66

# bold A ___________ is composed of two repeat units

Answer 66

copolymer

Question 67

____________ are usually copolymers.

Answer 67

Synthetic rubbers

Question 68

4 copolymer arrangement

Answer 68

Random Alternating Block Graft

Question 69

two different units are randomly dispersed along the chain

Answer 69

Random

Question 70

two repeat units alternate chain positions

Answer 70

alternating

Question 70

identical repeat units are clustered in blocks along the chain

Answer 70

block

Question 71

homopolymer side branches of one type may be grafted to homopolymer main chains that are composed of a different repeat unit

Answer 71

graft

Question 72

In ___________, the atomic arrangement in polymer materials are more complex as compared to metals and ceramics because in polymers it involves molecules instead of just atoms or ions.

Answer 72

crystalline state

Question 73

____________ is the packing of molecular chains to produce an ordered atomic array.

Answer 73

Polymer crystallinity